1. Field of the Invention
The field of the invention is data processing, or, more specifically, methods, apparatus, and products for load latency speculation in an out-of-order computer processor.
2. Description of Related Art
The development of the EDVAC computer system of 1948 is often cited as the beginning of the computer era. Since that time, computer systems have evolved into extremely complicated devices. Today's computers are much more sophisticated than early systems such as the EDVAC. Computer systems typically include a combination of hardware and software components, application programs, operating systems, processors, buses, memory, input/output devices, and so on. As advances in semiconductor processing and computer architecture push the performance of the computer higher and higher, more sophisticated computer software has evolved to take advantage of the higher performance of the hardware, resulting in computer systems today that are much more powerful than just a few years ago.
Modern computing systems can execute load instructions in which the content of memory is read into a processor register. Load instructions may experience a variety of problems which cause the instruction to require a longer execution latency period than the best case. Such problems can include missing the data cache, missing in the address translation mechanism, and so on. This variable latency complicates scheduling of dependent operations, as the dependent operations must issue before the load's latency is known to take advantage of the best case latency.